Railway-traffic-controlling apparatus



Feb 16, 1931. A. T. JOHNSTON 1,792,427

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 30, 1929 YCJW ATTORNEYPatented Feb. 10, 1931 UNITED STATES PATENT OFFICE ALLAN T. JOHNSTON, OFMOUNT LEBANQN,.PENNSYLVANI.A, ASS IGN OR TO THE UNION SWITCH & SIGNALCOMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION or PENNSYLVANIARAILWAY-TRAFFIG-CONTROLLING APPARATUS Application filed September 30,1929 Serial No. 396,042.

This invention relates to railway traflic controlling apparatus andparticularly to the provision of means effecting the release of afloating track relay upon the arrival of a train at a definite point ina track section. Where a floating relay is connected to a track sectionthe point in the section at which a train will release the relay oftenvaries considerably due to varying ballast resistance and train shunts.I have devised means which effectively provide for release of thefloating relay at a definite point, together with provisions afiordingan indication of or check against any failure of said means. l

I shall describe one form of apparatus embodying my invention andshallthen point out the novel features thereof in claims.

The accompanying drawing consists of a diagrammatic view illustrative ofmy invention.

Referring to the drawing, there is shown at 3 a section of railwaytrack, the two rails comprised in said section being designated 4:, 5,respectively. To the rails at one end of said section the coil 6 of atrack relay 6 is connected. The latter is shown as a standard form oftwo element relay, having a second winding 6", which is constantlyconnected with a source of alternating current not shown in the drawing.A track transformer 7 has its secondary 7 connected to the rails at theopposite end of said section for supplying current thereto. Connectedacross the track rails in parallel with said secondary 7 is a floatingrelay 8. In order .to provide for release of said floating relay uponthe arrival of a train at a definitepolnt in the track section, or, inother words, to provide a defi' nite shunting point for said relay, Iprovide an insulated joint9 at the selected point in one of the rails 4in saidtrack section, and

with rail 4; atone side of said joint Iconnect, as shown at 10,0neterminal of an impedance 11. The other terminal of said'irnpedance 'isconnected through wire '11 to a point 12 on the rail 15. The impedance.11

is shown .as forming the primary winding of a reactive transformer-l3,-comprising a core 1e. and a magnetic shunt 1%. Theses ing thevoltage on the left hand side to such a value'as will shunt the floatingrelay. The armature 17 of the latter will therefore not be released by atrain entering the track-section from the right until said train arrivesat the point 12. When the train passes the joint 9, it will shuntwinding 11, and the abrupt charge in the impedance of the track circuitwillopenrelay 8. A definite point for the shunting or release of thefloating relay 8 is thus provided.

t will be seen that the secondary winding 15 supplies to the rails atthe right hand side of joint 9, and hence to the track relay coil 6,current induced in said secondary by the connected as to apply to therails at the right hand side of the joint 9 instantaneous polarities thereverse of those applied by transformer 7 to the rails at the left ofsaid joint. If the insulated joint 9 should break down, the polarity ofthe rails at the right of said joint will be reversed owing to the factthat they are now directly connected to the track transformer 7. Suchreverse polarity appliedto the secondary iii-reduces the effectiveimpedance of the transformer unit, and this in turn reduces the voltagebetween the rails at said unit. The result of the application ofsaidreverse polarity is that there is an insuflicient flow of currentthrough the coil 6 of the track relay to hold up the-armature 18, andthe relay is released. It will be apparent that a short circuit or anopen cir' open circuit in either of the transformer windings, affords anindication that the impedance provided to establish a definite point forthe release of floating relay 8 is ineffective. A check against failureof said impedance is thus provided. Should the common connection 11 ofthe transformer winding to the rails 5 be broken, the impedance acrossthe joint 9 is increased, since the windings 14s and 15 are then placedin series with each other, and this will also result in release of relay6.

hile I have shown the impedance element 11 as a winding of a reactivetransformer it will be understood that a transformer other than one ofthe reactive type may be employed so long as the requisite amount of impedance is provided. Also, it may be noted that while I have shown butone insulated joint 9, an additional insulated joint may be provided inthe rails 5. Only one such joint is, however, required.

The terms and expressions which I have employed are used as terms ofdescription and not of limitation, and I have no intention, in the useof such terms and expressions, of excluding any mechanical equivalentsof the features shown and described or portions thereof, but recognizethat various structural modifications are possible within the scope ofthe invention claimed.

What I claim is:

1. In combination, a section of railway track, a track relay connectedto the rails adjacent one end of said section, a floating relayconnected to the rails adjacent the other end of said section, a sourceof current connected with the rails in parallel with said floatingrelay, an insulated joint in one rai of said section, an impedanceconnected across the rails of said section adjacent said insulatedjoint, and means for causing the first mentioned relay to be released inresponse to breaking down of the insulated oint.

2. In combination, a section of railway track, a track relay connectedto the rails adjacent one end of said section, a floating relayconnected to the rails adjacent the other end of said section, a sourceof current connected with the rails in parallel with said floatingrelay, an insulated joint in one rail of said section, an impedanceconnected across the rails of said section adjacent said insulatedjoint, and means for causing the first mentioned relay to be released inthe event that said impedance becomes ineffective.

3. In combination, a section of railway track, a source of currentconnected with the rails adjacent one end of said section, a fioatingrelay connected across the rails in parallel with said source, animpedance insuring release of said floating relay upon the arrival of atrain at a definite point in said section, and indicating meansresponsive to failure of said impedance.

4. In combination, a section of railway track, a floating relayconnected to the rails adjacent one end of said section, means insuringrelease of said floating relay upon the arrival of a train at a definitepoint in said section, and indicating means responsive to failure of thefirst mentioned means.

5. In combination, a section of railway track, a track relay connectedto the ra': adjacent one end of said section, a floating relay connectedto the rails adjacent the other end of said section, a source of currentconnected with the rails in parallel with said floating relay, aninsulated joint in one rail of said section, and a transformer havingone of its windings connected to said section at one side of said jointand the other of its windings connected to said section at the otherside of said joint.

6. In combination, a section of railway track including an insulatedjoint, a track relay connected to the rails adjacent one end of saidsection, a source of current connected to the rails adjacent the otherend of said section, a floating relay connected in parallel with saidcurrent supplying means and a transformer having a primary windingconnected to the rails of said section at one side of said insulatedjoint and having a secondary winding connected to the rails at the otherside of said joint in such man ner as to apply to said rails on suchother side of said joint a polarity the reverse of that applied by saidcurrent supplying IIIQZLIIS.

7. In combination, a section of railway track, a track relay connectedto the rails adjacent one end of said section, a floating relayconnected to the rails adjacent the opposite end of said section, asource of current connected with the rails in parallel with saidfloating relay, an insulated joint in one rail of said section, and areactive transformer connected to the rails adjacent said insu latedjoint.

8. In .combination, a section of railway track, a track relay connectedto the rails adjacent one end of said section, a floating relayconnected to the rails adjacent the other end of said section, a sourceof current connected with the rails in parallel with said floatingrelay, an insulated joint in one rail of said section, and a reactivetransformer one winding of which is connected to said section at oneside of said joint and the other winding of which is connected to saidsection at the other side of said joint.

9. In combination, a section of railway track, a track relay connectedto the rails adjacent one end of said section, a source of currentconnected to the rails adjacent the other end of said section, afloating relay connected with the rails in parallel with said source,and a reactive transformer one winding of which is connected to therails of said section for receiving current from said source and theother winding of which is connected to the rails of said section forsupplying current to said track relay.

10. In combination, a, section of railway track, a track relay connectedto the rails adjacent one end of said section, a source of currentconnected to the rails adjacent the other end of said section, afloating relay connected with said rails in parallel with said source,an insulated joint in said section, and a reactive transformer onewinding of which is connected to said section at one side of saidinsulated joint and the other winding of which is so connected to saidsection at the other side of said joint as to apply to the rails apolarity the reverse of that applied by said current supplying means.

11. In combination, a section of railway I track, a track relayconnected to the rails adjacent one end of said section, a floatingrelay connected to the rails adjacent the other end of said section, asource of current connected with the rails in parallel with saidfloating relay, an impedance connected across the rails at anintermediate point in said section for insuring release of the floatingrelay upon the arrival of a train at a definite point in the section,and means for causing release of said track relay in the event offailure of said impedance.

12. In combination, a section of railway track, a track relay connectedto the rails adjacent one end of said section, a floating relayconnected to the rails adjacent the other end of said section, a sourceof current connected with the rails in parallel with said floatingrelay, an insulated joint in one rail of said section, and a transformerhaving each of its windings connected on opposite sides of said joint toone series of the rails of said section, said windings being connectedthrough a common wire to the opposite series of rails.

In testimony whereof, I have signed my name to this specification this27th day of September, 1929.

ALLAN T. JOHNSTON.

